June 25, 1915. 



^ Experience Talks on Woodworking ^ 



One of the most annoying troubles experienced in mills and wood 

 working plants is with belting flapping on the slack side. Flapping 

 may be due to any one of several causes, or to a combination of them. 

 The most usual cause is that.one or both of the pulleys run out of true. 

 The belt is then alternately stretched and released, and while this 

 may not cause flapping at one speed, it will usually do so at a 

 higher speed. If the belt is rather slack, tightening it somewhat may 

 cure or alleviate the flapping. The most obvious and best remedy, 

 but the most expensive, is to turn the pulleys to run true. 



Covering the pulleys with leather reduces the slipping of belts 

 and also decreases the friction losses in belt driven transmission by 

 making it unnecessary to run the belts so tight. It is estimated 

 that leather covered pulleys will enable belting to transmit thirty 

 per cent more power than pulleys with the plain iron surface. 



In order to jirevent heavy stresses in shafts and bearings, pulleys 

 that are run at high speeds must be carefully balanced. Perfect bal- 

 ance involves two conditions: (a) the center of gravity of the 

 pulley must lie in the center lines of the shaft; (b) the straight line 

 joining the centers of gravity of any pair of opposite halves of the 

 pulleys must be perpendicular to the center line of the shaft. 



An old time, exjjerienced sawyer suggested to the writer that nine 

 thousand feet per minute — that is, nearly two )niles per minute — for 

 the rim of a circular saw to travel, may be laid down as a rule. He 

 states the following example : ' ' A saw twelve inches in diameter, three 

 feet around the rim, 3,000 revolutions; twenty-four inches in diam- 

 eter, or six feet around the rim, 1,500 revolutions; three feet in diam- 

 eter, or nine feet around the rim, 1,000 revolutions; four feet in 

 diameter, or twelve feet around the rim, 750 revolutions; five feet 

 in diameter, or fifteen feet around the rim, 600 revolutions. Of 

 course it is understood that the rim of a saw will run a little 

 faster than this reckoning, on account of the circumference being 

 more than three times as large as the diameter. 



Many of the progressive wood working plants are generating their 

 own electricity for power as well as lighting. Some of the boys 

 become very nervous when trouble arises at the dynamo or motor. 

 Sparking at the commutator is very common and it may be worth 

 the space to offer a few suggestions. If this be due to overload, the 

 sparking cannot be cured except by reducing the load. The trouble 

 may be due to improper position of brushes. Move the rock arm to one 

 side or the other to determine this. If copper brushes (tangential) 

 are used, they may be unevenly spaced around the commutator. Each 

 set of brushes should have the same relative position with regard to 

 respective pole tips. Sparking may be caused by an uneven com- 

 mutator, in which case it should be smoothed with sandpaper (not 

 emery) or turned down in the lathe. Sparking may also occur, in 

 a multipolar machine, from the wearing away of the bearings, which 

 produces eccentricity of the armature with respect to field, and con- 

 sequent unequal magnetic induction at different points. A slight 

 sparking at the brushes of the machine is not detrimental. 



Takes Exception to Article on Sap in Figured 

 Gum Panels 



The last issue Hardwood Record contained a short story regarding 

 the use of sap in figured gum panels suggesting that the use of too 

 much sap not only tended to give too splashy an appearance to the 

 panels, but also made them in a measure less durable. The story 

 urged the use of a thin line of sap contrasting with the dark wood, the 

 sap to appear at the joints, making a regular break in the whole 

 effect. Of course the whole suggestion was based on the condition 

 that the buyer himself desired this efifect. 



A prominent manufacturer in the South, who has made a specialty 

 of this work, writes as follows regarding the article : 



On page thirty-two you publish an article criticising the use of the 

 sap o£ figured gum panels. I have no idea where you got the information, 

 but there are a number of misleading statements in this article. In the 

 first place, the rules of the National veneer association specify that sap 

 wood in quartered oak, and it is understood in other figured woods, is no 

 defect. It has been attempted by the manufacturers of panels to work 

 sap world into their panels and tops, but the objection of the consumer 

 has been so strenuous that the panel maker has been obliged to dis- 

 continue It. I do not know of any manufacturers of figured gum panels 

 that have been tempted to use an excessive amount of sap in matching 

 up face stock, but I do know that with this wood, as with Circassian 

 walnut, there are occasional furniture manufacturers who believe that 

 a little sap wood worked into the joints does add to the effect, and their 

 ideas as to the relative quantity of sap wood vary. 



This article criticises the use of sap wood because it says there is a 

 tendency of the glue to come through and bring about a graying and 

 dingy effect. This effect, if it obtains, is not the fault of a first-class 

 panel manufacturer, but it is the fault of the finish that is put upon 

 the veneer. There is no more reason why joints in this wood should open 

 than in any other, and the wood should not be criticised for that cause, 

 1 do not see that the writer of the article has any reason to suggest that 

 some of the effects that he spreaks of are the "result of improper han- 

 dling by people who made up the panels." Nine times out of ten, bad 

 effects in veneered work are produced by improper finishing, yet In our 

 experience we have never found the head of a furniture factory who is 

 willing to admit that an error is possible in his finishing room. 



Sap wood can be used without becoming gray or cloudy in appearance 

 provided it is properly handled. This means that the glue must be prop- 

 erly dissolved, nut boiled or cooked, at proper temperature, and to a 

 Iiroper consistency. The glue must be applied as quickly as possible, 

 and the panels gotten under pressure quickly. Hot cauls must be avoided 

 as they will have the effect of drawing the glue through and giving the 

 sap wood the cloudy appearance that you complain of. The natural 

 finish will leave the wood white. It is true, however, that all white 

 woods become yellow in time. 



Open joints are a question of proper manufacture. It seems to me 

 that there is no more danger in sap wood than in the heart wood. 



Hardwood Record wishes to say that its intent was evidently mis- 

 understood in a measure as there was no desire to convey the im- 

 pression that the sap wood would cause opening up of joints, thus 

 making it possible for the glue to come through. On the other hand, 

 the slightly greater porosity of sap wood as compared to heartwood 

 makes it more easily possible for the glue to come through the pores, 

 and to appear eventually on the surface, which would cause, with the 

 wide white face at the joints, a slightly smudgy appearance in the 

 course of time. In a narrow strip of sap this would not be a notice- 

 able result. 



Hardwood Record welcomes these comments, and very gladly pub- 

 lishes this part of the letter. 



Is Chestnut Blight Subsiding? 



A large dealer in chestnut railroad ties in Pennsylvania announces 

 his belief that the chestnut blight which has done so much damage 

 to standing timber has about run its course and has ceased .spreading 

 into new territory. He says this observation holds true at least in 

 the portions of Pennsylvania where he is doing business. A great 

 deal of money has been spent by different states, especially by Penn- 

 sylvania, in combatting the chestnut disease and in trying to find 

 a remedy for it. As far as known, no practical headway has been 

 made in the fight ; but if the disease is now declining it is due to some 

 agency of nature not dependent upon what man has done. The dis- 

 ease is caused by a fungus that grows in the soft tissue between the 

 bark and the wood. 



Wood for Perches in Bird Cages 



In New Haven, Connecticut, there is a bird cage factory which 

 uses several car loads of lumber annually to make perches. The 

 wood must be strong, fine-textured, free of color, and not splintery. 

 Soft maple has been principally used in the past, but the company is 

 beginning to use white or paper birch instead. The wood is pur- 

 chased in the form of inch-and-a-quarter planks and is then cut up 

 and turned by automatic machinery. 



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